The subjective effects and degree of seeking or avoiding of nicotine will be compared among neversmokers (NS), ex-smokers (ES), current smokers (CS), and current smokers with a history of alcohol dependence. During a three-day exposure period, subjects receive three doses each day of either 0 mg, 2 mg or 4 mg nicotine gum in a double-blind, randomized crossover. Subjects provide subjective ratings (euphoria, liking, etc.) after each dose. On the fourth day, subjects (Ss) choose among the three types of gum to which they were exposed previously. Saliva samples will be analyzed in the GCRC Biochemistry Core Laboratory for levels of nicotine and cotinine.